If you open up the music manager, it shows you what tracks are uploaded while it does it, if it's matching you will just see the counter increased for number of tracks done

Bah. I downloaded the program back when the Scan and Match service was first made available for the UK and as far as I can tell it's scanned and matched nothing, and manually uploaded everything. (It's been almost a month and it's just about done 15,506 of 16,190 songs. My outgoing network data monitor correlates with the ~200GB worth of music it's uploading.